However, a transcriptome study of clinical PD samples gave a 1.6-fold higher level of HDAC6 expression and a 1.65-fold higher level of histone acetyltransferase1 (HAT1) expression [49,50], which is consistent with the increasing acetylation levels of H3 histone reported in the above studies [47,48]. This evidence concerns the gene HDAC6 and Parkinson disease.